1. Field of the Invention
The invention relates in general to a coupling effect reduction apparatus, and more particularly to a coupling effect reduction apparatus for reducing a charge coupling effect in an operational amplifier.
2. Description of the Related Art
In current technologies, an operational amplifier is often used as a voltage buffer that drives a load subsequently connected therefrom with a voltage. A voltage buffer generally functions with an output enable switch to perform associated timing controls. For example, when an output enable switch is turned off, an open circuit is accordingly presented between the voltage buffer and the load such that the voltage buffer is incapable of driving the load. In contrast, when the output enable switch is turned on, the voltage buffer is accordingly coupled to the load and is able to drive the load.
In practical situation, however, charge redistribution at an output node of the voltage buffer is also achieved when the switching operations, e.g. turning on or turning off, of the output enable switch take place. For a voltage buffer having an internal circuit design with a compensation capacitor or with circuit parasitic capacitance, the above occurrence of the charge redistribution could result in a coupling effect that causes a voltage of an internal node of the voltage buffer deviating from an originally designed level.